(FILES) In this file photo taken on July 27, 2019 US Ambassador to NATO and US special envoy for Ukraine Kurt Volker speaks during a press-conference in Kiev. - Kurt Volker, the US special envoy for Ukraine, resigned on September 27, 2019. Secretary of State Mike Pompeo on September 26 defended US diplomats' actions on Ukraine following reports that an envoy arranged contacts at the heart of a growing scandal. NBC News reported that Kurt Volker, the State Department special envoy on Ukraine, had put an official in Kiev in touch with Rudy Giuliani, the US president's lawyer who has championed the investigation of Joe Biden, the former vice president and Democratic frontrunner for the 2020 elections. (Photo by Sergei SUPINSKY / AFP)